On the applicability of model free isothermal prediction procedures for complex processes

Abstract

This paper analyses the possibility of using the model free isothermal prediction procedures for the complex processes. The validity of these procedures applied for complex processes is sometimes suspected because of some depressing results. It has been shown that the obtaining of arbitrary results by these methods is due to the assumption that the characteristic apparent activation parameters of the complex process depend only on the degree of conversion and that a correct prediction is obtained for any set of heating rates at which the necessary thermoanalytical data were recorded for applying the isoconversional method used. In order to obtain a satisfactory prediction, some “modified model free isothermal prediction procedures” have been suggested, which include an initial stage of determining the range of heating rates at which the thermoanalytical data necessary for the application of these procedures must be recorded, and in which it is considered that the apparent activation parameters depend both on the degree of conversion as well as the temperature for which the prediction is made. The validity of these modified procedures has been verified for simulated data corresponding to two complex processes, namely two first order parallel independent reactions and two first order consecutive reactions.